That's not the religious faith some of us are talking about. Faith has a couple definitions. From dictionary.com:
1. confidence or trust in a person or thing: "faith in another's ability."
2. belief that is not based on proof: "He had faith that the hypothesis would be substantiated by fact."
To me, you're invoking faith #1. Your boss trusted you because he knows you. You hope you make a difference because you understand what you're doing and have a plan. Farmers believe rain will come because it has rained in the past. Fishermen believe they'll catch something because there are fish in the water that are attracted to their bait. The hunter knows the herds will return to water because otherwise they will die.
One of the biggest parts of my journey from Christianity to Agnosticism was realizing that religious faith (faith #2), unlike so many other relevant parts of the Bible, had no place in my life. There's not a single decision I would make completely void of evidence or experience. Your boss didn't choose someone to send to Africa by picking a name from the phone book in the same way that the farmers, fishermen, and hunters don't sit in their homes and pray for baskets of food to appear on their doorstep when they awake in the morning. They have reason to believe (and hope, if that's where the choice of words differ) that what they're doing is going to work.
Hope that clarifies things a little!
Also, I should add, it's great to have your perspective in the conversation and I hope your work is going well.